I don't know of a list, but the easiest way to accomplish this is probably using OpenDNS. It's a free service that lets you choose from 50+ categories those that you find inappropriate (adult, social media, etc.) and it will block them. This is the same service used by thousands of schools, it works well, and for home use it is free. It's also a lot easier than trying to come up with your own list, and I'm almost certain that you can whitelist sites that you are ok with that get blocked.